Re: [PATCH v1 07/11] x86: perf: intel_pt: Intel PT PMU driver

Andi Kleen
2014-02-17T16:08:08Z

> So MAX_ORDER is 11, which gives us (11+12) 23bit or 8M max allocations, right?
>
> Given this TOPA stuff is completely fucked in the first release, that's
> about all we can get it, right?
>
> Now given you said 100s MB/s data rate for this itrace stuff, we're at
> ~0.1s traces. And that's in the very best case where we can actually get
> 8M.
>
> Is that a workable amount

The PMI handler switches to a new buffer to allow longer traces
in memory. It just costs one PMI.

-Andi

--
ak@linux.intel.com -- Speaking for myself only